Offspring delivered by opioid-exposed mothers often exhibit morphological biochemical, and behavioral abnormalities that involve the nervous system. This proposal hypothesizes that detectable errors occur during neuro-ontogeny in opiate-treated animals that might result in neurologic dysfunction and behavioral abnormalities. The proposed investigation is designed to elucidate the effects of perinatal (i.e., gestation and/or lactation) administration of methadone and heroin on the developing rodent brain, with particular reference to the cerebellum, hippocampus, and cerebrum. A major emphasis will be placed on morphology, and several research methods (histology, histochemistry, autoradiography, electron microscopy, freeze-fracture) will be utilized. Maternal withdrawal and nutritional responses in mothers and infants subjected to drug treatments will also be explored and correlated with structural observations. This research will be related to the human experience of illicit and therapeutic use of opiates during pregnancy and/or lactation and is intended to provide a basis for delineating and evaluating the immediate and long-term affects of transplacental postnatal exposure to narcotic agents.